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Repairing a Cello

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  • Repairing a Cello

    I have a decent quality student Cello (Cremona) that I bought new around 18 years ago. The Cello was never used and put in the back of a closet until recently. This Cello today costs around $900 to buy new. I tried to sell it, and a Cello expert came to see it, and pointed out some condition issues. The main issue is that the bottom of the Cello where the metal stand goes in and out has partially released from the top and the metal stand now is not straight with the Cello. The Cello also has a pronounced buzz when played. The good news is the Cello actually sounds quite nice and the expert said it would be worth fixing. He was not interested in it due to the issue. In order to fix it, I would need to remove the top of the Cello, fix the issue, then put the top back on. I am reading that most Cello tops are simply glued on with hide glue and that I can carefully cut through the glue with a knife to separate the top from the rest of the body.

    I think this would be a fun project with little to lose (I was offering the Cello for $350). I know we have some guitar makers on here and was wondering if anyone could advise me on how to remove the top of the Cello to inspect and fix whatever is under it.

    Click image for larger version

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  • #2

    Re: Repairing a Cello

    Check out this video, while this repair isn't similar to your problem, I think if you have a look thru his channel I'm sure you will find something related especially if the top is glued on with hide glue as many of his repairs involve hide glue. https://www.youtube.com/watch?v=zCCL9-3BjUU

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    • #3

      Re: Repairing a Cello

      Thanks I looked around I think it is just a butter knife carefully around the glue line. One guy heated up the knife using an iron to melt the glue. I am going to get some cheap threaded bar stock and a couple of 1" dowels and wingnuts along with a piece of fabric to make some clamps to put it all back together. Seems like I will need around 40 clamps. None of the sites or videos I saw said anything about refinishing the part of the top that is put back on. So not sure what to do with that I'll see how it looks when it is back together. I'll post up pics if anyone is interested.

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      • #4

        Re: Repairing a Cello

        I can't speak for the others but I am interested in your repair effort so please post pictures as you go. I, for one, would appreciate that. If the cello is glued together with hide glue (as it should be), warming will help you ease it apart but the finish is susceptible to damage from the heat too (likely to be a lacquer finish) but you probably already discovered that.

        Good luck with it

        Ken
        schor likes this.

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        • #5

          Re: Repairing a Cello

          Originally posted by WoodBob View Post
          I am going to get some cheap threaded bar stock and a couple of 1" dowels and wingnuts along with a piece of fabric to make some clamps to put it all back together.
          CAVEAT : I an NOT an instrument woodworker. I have seen images of instruments held together after repair and gluing by using surgical silicone tubing wrapped and wrapped and wr.... etc. Maybe an idea?

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          • #6

            Re: Repairing a Cello

            I would also be interested in how the repair goes. I have a violin of great sentimental value,but little monetary value that appeared to simply need to be glued back together

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            • #7

              Re: Repairing a Cello

              Often these are assembled with hide glue which will loosen with heat. To John's comment, Luthiers will often use twine, rope or rubber tubing to apply gluing pressure to the top for assembly or alternatively spool clamps. You may have to carve some sort of additional thin bracing at the bottom to support the repaired stand.

              There are lot's of books on Luthiery and also many other forums where you could ask and receive excellent, informed answers like I am completely unable to provide....

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              • #8

                Re: Repairing a Cello

                Originally posted by al.m.. View Post
                I would also be interested in how the repair goes. I have a violin of great sentimental value,but little monetary value that appeared to simply need to be glued back together
                I also have the violin that my mother was given by the uncle and aunt who raised her. She got it (used) in the late 1930's and it needs some TLC, so I'll be watching this thread with much interest.

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                • #9

                  Re: Repairing a Cello

                  I've took off a cello top only once & it was not a difficult task to achieve,maybe yours is different.

                  It can be done quite easily with a thin metal blade that you work in to the hide glue joint slowly & patiently.

                  If the blade is heated just enough to melt the glue but not too much in order to affect the lacquer finish everything's fine.& the finish wiil remain the same , no need to fix it once the re-gluieing is done.

                  What is more concerning however is that cellos are usually assembled in a mold that keeps the sides (ribs) straight so you may encounter some alignment problems i.e top versus ribs when trying to put the top back on the instrument for glueing.A surgical tubing has enough power for the glueing job imho.

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                  • #10

                    Re: Repairing a Cello

                    Click image for larger version

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                    • #11

                      Re: Repairing a Cello

                      The game is afoot! I started up heating up a thin scraper but while I was waiting I stuck in an old kitchen knife. It was very easy to break the hide glue bond. In under 10 minutes I had the top off with no heat. An inspection shows the issue. The foot block is cracked. I think I can just glue it back together and then use a length of oak to re-position the tail piece to where it is supposed to be. I would also laminate a piece of ply over the cracked block. I am not sure if this will do anything to the sound. I can't imagine much of a change. I also considered a guitar truss rod in the same location. I can push that section out with my hand with just a small bit of force and put it back in the proper location so I think a brace would be a good permanent solution. It will also prevent it from happening again. Really I see no other way to fix the "ribs" without redoing the entire thing. You can see my wonderful luthier tools all laid out.

                      Beaverfever1988 likes this.

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                      • #12

                        Re: Repairing a Cello

                        Can you get that old block out? If so, then making a new one might be best.

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                        • #13

                          Re: Repairing a Cello

                          Originally posted by drzaius View Post
                          Can you get that old block out? If so, then making a new one might be best.
                          That was my first inclination when I saw it. I just don't see an easy way to get it off without doing major damage to the ribs. It seems like once glued back together, laminated, and with my oak "truss rod" it'll be very solid.

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                          • #14

                            Re: Repairing a Cello

                            I went ahead and glued the broken pieces back in the 2 main places. Once that is dry, I will add the lamination piece which I already cut out of 1/4" plywood. I started shaping my makeshift truss rod but not sure I will need it. If the 2 pieces stay glued I think that will re-position the foot peg correctly. Have to wait and see.

                            Also there is a wood dowel in the Cello that fell out when I took the top off. It looks like it is just jammed in between the top and the bottom to add support. I can see where it was before due to the light marks it made but I am not sure how this was added to the Cello. Does anyone know? It looks like it was placed possibly through the f holes and just jammed in there.

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                            • #15

                              Re: Repairing a Cello

                              The '' dowel '' is the sound post.

                              It is set between the top and the back & it's placement can affect the sound pretty much.You'll have to play a bit with it in order to get the best sound the cello can produce.

                              Ideally u should put it back at the same spots , quite easy for the back but not so much for the top.

                              I've posted some pics above about the tool that is used to place the post back & yes it is done through the ''F'' holes.

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